im gathering the pressure only goes up above 2.5 when you have you heating on it depends on what the pressure was when the boiler was cold it should normally be between 1-1.5 in the green section the pressure will always rise when you have your heating on slightly it may be your filling loop it not closed off properly and continuosly passing unlikley i think i would suggest a problem with the expansion vessel having lost its pressure do you have water escaping from the blow off outside if so i would sugest expansion vessel may need re pressurised or renewed
byron, October 2010
